1. Field of the Invention
This invention relates to a terminal apparatus for use in a communication network, and particularly to a communication terminal apparatus capable of handling a mixture of graphic information and character information.
2. Description of the Prior Art
Standardization of Group 4 facsimile machines (hereinafter also referred to as G4 machines) is being under way at CCITT. G4 machines are directed to improvements over Group 3 facsimile machines, for example, in resolution and transmission rate, and also to the provision of so-called "telematic service" for handling a mixture of graphic and character information. G4 machines are classified into three classes depending on the function. A class 1 G4 machine is functionally a simple facsimile machine so that it cannot receive or transmit character information at all. A class 2 G4 machine is provided with a function to receive character information in addition to the usual facsimile function, so that it can receive character information but it cannot transmit character information.
On the other hand, a class 3 G4 machine has a function not only to receive but also to transmit a mixture of graphic and character information. For this reason, the class 3 G4 machine is provided with a screen editor unit, thereby allowing an operator to insert character information into graphic information or graphic information into character information to create new information to send by looking at the screen of display unit, such as a CRT display unit. The new information thus created is once stored in an image memory, and, thus, in principle, a memory-to-memory communication is carried out in the case of G4 machines.
Under the circumstances, if desired to send a mixture of graphic and character information from a class 3 G4 machine to a class 1 G4 machine, a following problem will be encountered. That is, since the class 1 machine is not so structured to receive character information as described above, the mixture information to send must first be reproduced on a sheet of paper at the class 3 machine, and, then, the sheet of paper having thereon the reproduced mixture information must be optically read by a scanner thereby converting the mixture information to all graphic information. Such an operation is cumbersome and it can cause lowering of transmission efficiency.